1. Field of the Invention
The present invention relates to 2,5-bis-(1',1'-dimethylbutyl)hydroquinone and to a process for producing the same.
2. Description of the Prior Art
Alkylhydroquinones are useful as an antioxidant for rubbers. For example, 2,5-di-t-butylhydroquinone has been produced on an industrial scale and is commercially available (refer to Handbook of Compound Chemicals for Rubber-Plastics, issued by Rubber Digest Co., 1966, 6, 1). Further, alkylhydroquinones are used as an antifogging agent for silver halide photographic sensitive materials. For example, U.S. Pat. No. 2,728,659 discloses that 2,5-di-n-dodecylhydroquinone is suitable for such a purpose.
However, as described in the above-described Handbook of Compound Chemicals for Rubber-Plastics, the blending of di-t-butylhydroquinone with rubber requires a long time, because it has a melting point above 200.degree.C. If a method for reducing the melting point by introducing a substituent having more carbon atoms than the t-butyl group is applied, a good effect can not be obtained in the case of a t-amyl group, because the melting point of such a compound is above 172.degree.C (refer to the above-described Handbook of Compound Chemicals for Rubber-Plastics). Further, though rapid blending can be expected using 2,5-bis-(1',1',3',3'-tetramethylbutyl)hydroquinone (melting point: 132.degree.C) which has an alkyl group having more carbon atoms as the substituent, the yield in the production thereof is very low. It is difficult to say whether the compound would be inexpensive even if an improved process for synthesis as described in Japanese Patent Publication 2346/1967 is used.
Further, where an alkylhydroquinone is used by incorporation in silver halide photographic sensitive materials as described in U.S. Pat. No. 2,728,659, there is a serious defect too that crystals easily precipitate because of the high melting point.